Electrode Potential Evaluation of Effect of Inhibitors on the Electrochemical Corrosion Behaviour of Mild Steel Reinforcement in Concrete in H2SO4ud

摘要

The electrochemical corrosion behaviour of mild steel embedded in concrete, and partially immersed in 0.2MudH2SO4, was studied in this investigation at ambient temperature by potential monitoring technique. Theudexperimental work was performed with a digital multimeter and a Cu/CuSO4 electrode (CSE) as the referenceudelectrode. Extracts of carica papaya leaves and sodium nitrite (NaNO2) in different concentrations wereudseparately and in combination, used as inhibitors. This paper reports the observed electrochemical responseudfrom the electrode potential monitoring of the embedded steel rebar during the experiments. The resultsudobtained, showed a reduction in the active corrosion reactions behaviour of the embedded mild steel inudconcrete with added different concentrations of sodium nitrite and the pawpaw leaves extracts in the acidicudtest environment. This reduced active corrosion reaction was an indication of corrosion inhibition / protectionudcharacteristic. The observed inhibition was associated with the protective film provided on the embeddedudsteel’s surface in the concrete by the complex chemical compounds of the plant leaves’ extracts and of theudsodium nitrite with the alkaline composition/environment of the concrete constituents. The protective filmudprevented and/or reduced the chloride ions penetration to the steel surface. The combination of c. papayaudextracts and the NaNO2 solution also provided effective corrosion inhibition of the embedded steel byudsynergism. The 100% concentration of each of the inhibitors and when in combinations, exhibited the mostudeffective corrosion inhibition performance in the sulphuric acid test environment.ud